how to make SAI1 mclk & MQS to work on IMX6UL evk?

It seems some other people have encountered similar issues in i.MX community, but I just can't find a solution that can help.

I am trying to enable MQS audio on IMX6UL evk board. there are apparently some examples already in the kernel, e.g. device tree imx6ul-14x14-ddr3-arm2-mqs.dts. I copied these stuff, and could play audio on sound card mqs-audio, but no audio heard or PWM signal observed, so mqs is not working.

It looks like the SAI1 is more or less working, because we can see the TX data signal and bit clock on oscilloscope, but couldn't see MCLK output, here are the pin mapping we are using in device tree:

I noticed there is a patch in mainstream kernel to enable "fsl,sai-mclk-direction-output" in device tree, but this patch does not work for us. I think the reason is obvious, it was trying to set the bit 19 of IOMUXC GPR1, which is only useful when pad LCD_DATA00 pin is used for MCLK output (I am using CSI_DATA01)

Regardless, from my point of view, SAI1 MCLK do not need to output to any pin as long as it can be correctly propagated to MQS, but what should I do other than following lines in device tree:

Thanks for answer, If you are talking about SAI1_MCLK_DIR bit in IOMUXC_GPR1 (bit 19), yes, we did set this bit. But it still does not work. Looking at the IM6ULRM, the bit is only necessary when SAI1.MCLK is configured for LCD_DATA00 mode ALT8. I tried LCD_DATA00 and CSI_DATA01 for MCLK pin output, do not see difference.